Generally, a heating element converts electricity into heat and transfers the heat to the outside through radiation to transfer energy. Such a heating element has been generally and widely used in various home appliances or various industrial fields.
Heating elements can be roughly classified into metallic heating elements, nonmetallic heating elements, and other heating elements depending on materials thereof. The metallic heating elements including a Fe—Cr—Al-based heating element, a Ni—Cr-based heating element, and a high melting point metal (platinum, Mo, W, Ta, and the like)-based heating element were mainly used in the early days. The nonmetallic heating elements including silicon carbide, molybdenum silicide, lanthanum chromite, carbon, zirconia, and the like have been used thereafter. Further, the other heating elements including a ceramic material, barium carbonate, a thick film resistor, and the like have been used.
The heating elements can be classified into linear heating elements typically called “heating wire” and sheet heating elements depending on outer shapes thereof. By way of example, the linear heating elements include a filament and a nichrome wire. The sheet heating elements generally include heating elements each comprising metallic electrodes provided on both ends of a thin sheet-shaped conductive heating material and insulation-processed with an insulation material and generating heat from all over the surface and may use a metallic thin sheet, heating paint (carbon black), and carbon fiber.